Remediation effect of mercapto-palygorskite combined with manganese sulfate on cadmium contaminated alkaline soil and cadmium accumulation in pak choi (Brassica chinensis L.).

Cadmium pollution in alkaline soil in some areas of northern China seriously threatens agricultural production and human health, but there are few materials and methods to remediate cadmium pollution in alkaline soil. Therefore, it is necessary to further study the economic and adaptive remediation and regulation techniques of cadmium pollution in alkaline soil. In the study, a pot experiment was conducted to study the effects of MP and MnSO combined treatment on the immobilization effect of cadmium contaminated alkaline soils. The results showed that LM and HM treatments in different periods had little effect on the content of extractable Cd fraction in soil without MP treatment, but the EXC-Cd content in the soil with Mn(15) was lower than that in the soil with Mn(29). The EXC-Cd content under MP+ LM and MP + HM treatments reduced by 3%-7% and 7%-9%, respectively. The OX-Cd content increased by 13%-16% after MP + Mn treatment. The content of DTPA-Cd decreased by 17.9%-28.6% under MP + Mn treatment except for MP + HM(15). Under the treatment of MP, LM(29), HM, MP + LM and MP + HM, the content of Cd in shoots of pak choi were decreased by 27.2%, 13.1%, 19.8%-27.9%, 28.5%-54.2% and 34.2%-41.1%, respectively. Compared with CK, the TF values in HM(15), LM(29), HM(29), MP + LM(29) and MP + HM(29) treatments were reduced to 35.7%, 41.1%, 35.7%, 42.9% and 37.5%, respectively, while no statistical difference was observed in other treatments. There was no significant difference in BCF between MP(15) and LM(15), but the BCF was significantly decreased. For MP + MnSO treatment group, the content of Mn oxides in soil was negatively correlated with the content of EXC-Cd (P < 0.05) and positively correlated with the content of OX-Cd (P < 0.05).